The present invention relates to a rate-of-climb indicator to be mounted in an airplane for maintaining level flight or a predetermined altitude change. More particularly, the invention relates to a rate-of-climb indicator for indicating the existence of any wind shear, and which can show the intensity of a gust and change of lift at the time of take-off or landing of the airplane.
In order to show the rate of altitude change for airplanes, a rate-of-climb indicator has conventionally been used. FIGS. 1(A) and 1(B) show an example of such a rate-of-climb indicator, FIG. 1(A) showing a front view thereof and FIG. 1(B) a partly broken perspective view of the indicator. In the conventional rate-of-climb indicator shown in these figures, a differential pressure is generated with the utilization of a capillary tube 2 and this is measured by a highly sensitive open-type capsule 3. The inner pressure within the capsule 3 varies according to the change of the static pressure connected to the capsule 3. On the other hand, the outer pressure of the capsule 3, that is the inner pressure of a case 1 changes gradually through the capillary tube 2. The displacement of the capsule 3 due to the differential pressure is transmitted to a pointer 4 through an amplifying mechanism 5.
With the above mentioned type rate-of-climb indicator, the rate of altitude change of the airplane can be known.
Even with the use of this kind of rate-of-climb indicator, an airplane flying at a low altitude might be exposed to an unexpected danger because of the existence of wind shear which suddenly changes its blowing directions. The problem of the influence of wind shear at the time of take-off and landing of the airplane is explained with reference to FIGS. 2(A) and 2(B).
FIG. 2(A) shows the landing of the airplane A. Assume that the airplane A, which has been in horizontal flight, starts descending from a point (a) for a landing strip G along a glide slope shown by the solid line. The airplane can land along the glide slope when there is no wind or when there is a constant wind speed condition. On the other hand, if a head wind occurs suddenly, the airspeed increases and the airplane lifts over the glide slope as shown in the dotted line (b). In case the wind blows from behind the airplane, the airplane flies under the glide slope as shown in the dotted line (c).
FIG. 2(B) shows the take-off of the airplane. If the airplane A which took-off at the point (d) receives a sudden wind from behind, its body is lowered from the solid line of the figure, as shown in (e). When the wind changes direction and the airplane receives a head wind, its body lifts as shown in the dotted line (f).
A sudden lift or lowering at the time of landing or take-off of the airplane is very dangerous, and might be the cause of many airplane accidents.